It was not, the commentators all agreed, a vintage night for British talent. But while all lenses were focused on Carey Mulligan and Colin Firth trying to look gracious in defeat, the success of two of their compatriots went almost unnoticed.

Sandy Powell's triumph in the Best Costume Design category meant she has now won more Oscars than Marlon Brando, Meryl Streep and Robert De Niro – all of whom have just two to her three. "I already have two of these, but I'm feeling greedy," ran the provocative opening line of her acceptance speech, a quip which went down badly at a ceremony where faux modesty rules the day.

The other British winner was Ray Beckett, who won his first Oscar with colleague Paul Ottosson for sound mixing on The Hurt Locker, Kathryn Bigelow's acclaimed but little seen thriller about a bomb disposal team in Iraq, which proved to be the underdog victor. The low budget film scooped six awards including Best Picture, Best Original Screenplay and Best Director – making Bigelow the first woman to take directing honours in Oscar history.

Sandra Bullock beat Meryl Streep, along with British nominees Mulligan and Helen Mirren, to win Best Actress, and Jeff Bridges got his long-awaited due as Best Actor for his role as a washed-up country music star in Crazy Heart, beating Firth in the process. The record-breaking blockbuster Avatar, meanwhile, came away with little more than crumbs – its role at the awards ceremony being, apparently, to use its box-office heft to try to draw bigger television audience ratings.

All sorts of fights that might have broken out didn't. The widely predicted smackdown between Bigelow and her ex-husband, Jim Cameron, Avatar's visionary director, did not happen. Rather, Cameron sat directly behind Bigelow and didn't seem to mind her moment of glory one bit.

The most unambiguous hostility came in the most unlikely of places, the documentary short category, whose winners provided easily the strangest episode of the night. Roger Ross Williams, director of Music By Prudence, a film about disabled musicians in Zimbabwe, started an acceptance speech only to have the microphone wrested away from him by one of his producers, Elinor Burkett.

Williams later accused Burkett, with whom he has not been on speaking terms for more than a year, of pulling a "Kanye" (after Kanye West's interruption of Taylor Swift's acceptance speech at at this year's video music awards). Burkett countered that Williams had improperly hogged the podium.

The British contingent did nothing so outrageous, mainly because they came away almost completely empty-handed.

But 49-year-old Powell was again recognised as one of the best costume designers in the business. Her latest Oscar, for costume drama The Young Victoria, will sit alongside identical statuettes for her work on The Aviator and Shakespeare in Love.

Known as a force to be reckoned with – Scarlett Johannson said last year she wouldn't dare talk back to Powell – she said most of her job involves sweet-talking thespians into doing what she wants. "Eighty per cent of the job is psychology, and only about 20 per cent art," she told the Times in 2008. "You should be of the temperament to deal with all types of people and understand very quickly how to get the best out of your department, get your own way with actors and fulfil your role helping to create your director's vision."

This year's Oscars were touted as many things. The producers of the telecast promised innovation and a fresh look, but delivered the same old pomposity, tired jokes, bad dance routines and endless montages.

What was most striking, in the end, was the large number of African-Americans in attendance and on the winner's podium. Precious was a big part of that – screenwriter Jeffrey Hatcher won an Oscar alongside Mo'Nique, and newcomer Gabourey Sidibe earned just as much attention for her Best Actress nomination as Mulligan. But there was also Morgan Freeman (nominated for playing Nelson Mandela in Invictus), Avator star Zoe Saldana (who presented an award but was not up for any) and a clutch of other black stars including Queen Latifah and Sam Jackson.

Has Hollywood finally become colour-blind in the age of Obama? Perhaps. Sidibe, who was plucked out of a New York community college to play the lead in Precious, also brought a refreshing dose of street reality to the pampered environment of the film biz. Asked on the red carpet about her dress – which, like her, was several sizes larger than the Hollywood norm – she shot out with delicious vulgarity and a huge smile: "If fashion was porn, this dress would be the money shot."

• This article was amended on 9 March 2010. The original named one British winner as Rob Beckett, and said his award was for sound editing. This has been corrected.

... from behind the cordon, of course. But wait, be dazzled by best actress Sandra Bullock, catch a glimpse of the triumphant Christoph Waltz and marvel at the mighty shoulder-pads of Joan Collins in our Oscars after-parties gallery. Xan Brooks is the virtual belle of the ball

Kathryn Bigelow and co gave him a loving shout-out on Sunday evening as they picked up the Academy Award for best picture; Chartier delivered his own acceptance speech from Malibu yesterday. But who is the man Oscar stopped at the door?